7. PROJECT SUMMARY/ABSTRACT Complications of diabetes such as retinopathy, renal failure, amputation, stroke, and myocardial infarction have a major impact on the wellbeing of patients with diabetes and cause high rates of death. To delay progression of complications, control symptoms, and prevent mortality, a spectrum of medical care is needed including high acuity physician visits, advanced diagnostic tests, and invasive therapy. A rapidly growing form of health coverage - high-deductible insurance - substantially increases patients' out-of-pocket costs for such services. Families in high-deductible health plans must pay up to $12,000 per year before more comprehensive coverage begins. High cost-sharing levels are intended to encourage more efficient and higher quality care but could also reduce access to services that treat complications and save lives. It is essential to understand how high-deductible health plans affect micro- and macrovascular outcomes in diabetes. Suboptimal access could reduce detection of complications, accelerate disease progression, and increase deaths. This proposal seeks to assess the impact of high-deductible health plans on micro- and macrovascular diabetes complications and on the care that affects them, including physician visits, diagnostic testing, and major therapies. Our measure of physician visits will comprise outpatient and emergency department visits with specific diagnoses potentially related to diabetes complications, and we will classify emergency department visits as high or lower severity. The diagnostic tests we will examine include retinal imaging, renal biopsy, peripheral angiography, advanced brain imaging, and cardiac catheterization. We will further assess whether tests for coronary heart disease are used inappropriately to screen patients with diabetes. Our composite measure of therapy for macrovascular complications will include lower extremity bypass grafting, thrombolysis, and coronary artery stenting. To assess health outcomes, we will examine a composite measure of microvascular complications assessing treatment for advanced retinopathy and need for dialysis or renal transplant. Our composite macrovascular outcome will include lower extremity amputation, myocardial infarction, stroke, and death. This study will include a 15-year rolling sample of 71,000 diabetes patients whose employers mandated a switch from traditional to high-deductible health plans. We will use employer- and member-level propensity score matching to minimize selection bias. The study will employ strong quasi-experimental designs including interrupted time-series with comparison series and Kaplan-Meier survival curves to examine outcomes of interest. This project will be the first to examine these research questions on a national scale.